"Paul Walker -- best known for his role in "The Fast and the Furious" movies -- died Saturday afternoon after a single-car accident and explosion in Southern California ... TMZ has learned.

The accident happened in Santa Clarita -- north of Los Angeles -- and according to multiple sources connected to Paul ... the actor was in a Porsche when the driver somehow lost control and slammed into a post or a tree ... and then the car burst into flames.

Several of our sources -- some who are still at the scene of the accident -- tell us Paul and another person in the car were killed. Law enforcement is still on the scene, and we're told the L.A. County Coroner's Office is on the way."

Please at least look around a little on the forums when you post this kind of thing - it was the second thread from the top when you posted this. Chances are if there is major news, someone got to it before you did.